Reduced stiffness barrel fired projectile

Abstract

In various embodiments, a projectile includes a projectile body including a tail portion, a nose portion, a barrel engaging portion between the nose portion and the tail portion, and a metal jacket that defines an exterior of the projectile that surrounds an interior solid core. In one or more embodiments the projectile includes one or more circumferential grooves defined in the interior core portion, each of the one or more circumferential grooves covered by and positioned adjacent to the metal jacket and within the barrel-engaging portion. In various embodiments, during firing of the projectile, the one or more circumferential grooves define a void that allows material of one or more of the metal jacket and interior solid core to displace into the void for reduction in radial stiffness to the projectile in the barrel engaging portion.

What is claimed is: 
     
       1. A projectile comprising:
 a projectile body including a nose portion, a barrel engaging portion rearward of the nose portion, and a metal jacket that extends forwardly to at least the nose portion and defines an exterior of the projectile that surrounds a core, the core comprising a forward penetrator portion making up a most forward portion of the core and a plug portion that is positioned rearward of the penetrator portion, the portions of the projectile body being arranged along a central longitudinal axis; and 
 two or more axially extending grooves spaced circumferentially apart by exterior surface portions of the plug portion of the core, each of the two or more axially extending grooves covered by and positioned adjacent to the metal jacket and within the barrel-engaging portion, each of the two or more axially extending grooves having an axial extent, a circumferential extent and a radial depth, and the axial extent is substantially the length of the barrel-engaging portion; 
 wherein circumferential spacing between the axially extending grooves is greater than the circumferential extent of the two or more axially extending grooves; 
 the metal jacket comprising an interior surface, a majority of the interior surface along the barrel-engaging portion contacting the plug portion; 
 wherein during firing of the projectile, the two or more axially extending grooves define a void that allows material of one or more of the metal jacket and core to displace into the void for reduction in radial stiffness to the projectile in the barrel engaging portion. 
 
     
     
       2. The projectile of  claim 1 , wherein the two or more axially extending grooves extend parallel to the central longitudinal axis. 
     
     
       3. The projectile of  claim 1 , wherein the two or more axially extending grooves comprise helical grooves. 
     
     
       4. The projectile of  claim 1 , wherein the plug portion of the core comprises a cross-sectional shape that defines voids between the plug portion and the metal jacket and along the two or more axially extending grooves. 
     
     
       5. The projectile of  claim 1 , wherein the two or more axially extending grooves are defined only in the plug portion of the core, and
 wherein the plug portion comprises a tapered boat tail portion, and the two or more axially extending grooves extend into the boat tail portion. 
 
     
     
       6. The projectile of  claim 1 , wherein the nose portion comprises a tip portion that forms a spitzer aerodynamic shape for the projectile and that defines a most forward portion for the projectile, and
 wherein the penetrator portion of the core is composed of a material having a stiffness as measured by Young's modulus greater than 20 Mpsi, and the plug portion of the core is composed of a material having a stiffness as measured by Young's modulus in the range of 10 Mpsi to 30 Mpsi. 
 
     
     
       7. The projectile of  claim 6 , wherein the metal jacket extends to one of:
 a termination at a forward portion such that the tip portion is an exposed portion of the penetrator portion not covered by the metal jacket, the tip portion having an exterior surface substantially flush with an exterior surface of the metal jacket and extending from a rearward portion to a forward point of the projectile, or 
 covering the entirety of the core including the tip portion. 
 
     
     
       8. A projectile comprising:
 a projectile body comprising a nose portion, a barrel engaging portion rearward of the nose portion, and a metal jacket that extends forwardly to at least the nose portion and defines an exterior of the projectile that surrounds a core, the portions of the projectile body being arranged along a central longitudinal axis; and 
 one or more non-circumferential grooves defined in the core and not in the metal jacket, each of the one or more non-circumferential grooves being covered by the metal jacket and being located within the barrel-engaging portion; 
 the metal jacket comprising an interior surface, a majority of the interior surface along the barrel-engaging portion contacting the core; 
 wherein during firing of the projectile, the one or more non-circumferential grooves define a void that allows material of one or more of the metal jacket and core to displace into the void for reduction in radial stiffness to the projectile in the barrel engaging portion. 
 
     
     
       9. The projectile of  claim 8 , wherein each of the one or more non-circumferential grooves comprises an axially extending groove extending parallel to the central longitudinal axis. 
     
     
       10. The projectile of  claim 8 , wherein each of the one or more non-circumferential grooves comprises an axially extending helical groove. 
     
     
       11. The projectile of  claim 8 , wherein the core comprises a cross-sectional shape that defines one or more voids between a plug portion and the metal jacket and along the one or more non-circumferential grooves. 
     
     
       12. The projectile of  claim 8 , wherein the core comprises a tapered tail portion, and each of the one or more non-circumferential grooves comprises an axially extending groove that extends into the tapered tail portion. 
     
     
       13. The projectile of  claim 8 , wherein, each of the one or more non-circumferential grooves comprising an axially extending groove that comprises an axial extent and a radial depth, and the axial extent is substantially the length of the barrel-engaging portion and the radial depth is in the range of 0.1 inches to 0.0025 inches. 
     
     
       14. The projectile of  claim 8 , wherein the one or more non-circumferential grooves extend inwardly 4% to 15% of a diameter of the projectile in the barrel-engaging portion. 
     
     
       15. The projectile of  claim 8 , wherein the core is composed of one or more of aluminum, antimony, beryllium, bismuth, boron carbide, brass, bronze, chromium, cobalt, copper, gold, iridium, iron, lead, magnesium, mercury, molybdenum, nickel, palladium, platinum, rhodium, silicon carbide, silver, steel, tantalum, tellurium, tin, titanium, tungsten, tungsten carbide, depleted uranium, zinc and zirconium, and an alloy,
 wherein the core comprises two or more portions where each portion is composed from a different material, and 
 wherein the core comprises a forward penetrator portion making up a most forward portion of the core and a plug portion that is positioned rearward of the penetrator portion, and 
 wherein the penetrator portion is composed of materials having a high stiffness or lesser malleability than one or more of the metal jacket and the plug portion. 
 
     
     
       16. The projectile of  claim 15 , wherein the penetrator portion is composed of steel and the plug portion is composed of one or more of copper, brass, a copper alloy, and lead. 
     
     
       17. The projectile of  claim 8 , wherein the core is a unitary core composed of a single material. 
     
     
       18. The projectile of  claim 8 , wherein the nose portion comprises a tip portion that forms a spitzer aerodynamic shape for the projectile and that defines a most forward portion for the projectile,
 wherein the metal jacket terminates at a forward portion such that the tip portion is an exposed portion of the core not covered by the metal jacket, the tip portion having an exterior surface substantially flush with an exterior surface of the metal jacket and extending from a rearward portion to a forward point of the projectile, and 
 wherein the tip portion is a polymer tip. 
 
     
     
       19. The projectile of  claim 18 , wherein the nose portion comprises a tip portion that forms a spitzer aerodynamic shape for the projectile and that defines a most forward portion for the projectile, and
 wherein the metal jacket covers the entirety of the core including the tip portion. 
 
     
     
       20. A projectile cartridge comprising:
 a casing comprising an upper lip slightly swaged inwardly onto a projectile seated in the casing to form a seal with respect to an interior of the casing; and 
 a quantity of propellant included along with a primer for initiating detonation of the propellant and for firing the projectile; 
 wherein the projectile comprises:
 a projectile body comprising a nose portion, a barrel engaging portion rearward of the nose portion, and a metal jacket that extends forwardly to at least the nose portion and defines an exterior of the projectile that surrounds an interior core portion, the portions of the projectile body being arranged along a central longitudinal axis; 
 the metal jacket comprising an interior surface within the barrel-engaging portion; and 
 one or more grooves defined in the interior core portion and comprising a radial depth below an exterior surface of the interior core portion, each of the one or more grooves covered by and positioned adjacent to the metal jacket and within the barrel-engaging portion, the exterior surface portion configured to interface with the interior surface of the metal jacket to increase the surface area contact between the interior core portion and the jacket; 
 
 wherein before firing of the projectile, a majority of the interior surface of the metal jacket within the barrel engaging portion is in contact with the exterior surface portion; 
 wherein during firing of the projectile, the one or more grooves define a void that allows material of one or more of the metal jacket and interior core portion to displace into the void for reduction in radial stiffness to the projectile in the barrel engaging portion.